With the popularization of computer technology, touch screen technology is developed as a new technology of human-computer interaction in the early 1990s. Using this technology, a user can operate a computer just by gently touching graphics or texts in computer screen with a finger or a stylus etc., which gets rid of restrictions of keyboard and mouse and brings considerable convenience to the user.
The touch screens commonly used now include infrared touch screen and touch screen with camera. The infrared touch screen uses plenty of infrared emitters and infrared receivers which correspond to each other for determining location information of a touch object, and its working principle is simple. However, as the infrared touch screen requires plenty of infrared elements and installation and test thereof is complicated, the production cost is high. Moreover, as the infrared emitters and infrared receivers are prone to aging, the infrared touch screen has poor reliability. Conversely, the touch screen with camera is widely used as its simple structure, low cost, easy production and high reliability.
The touch screen with camera usually comprises two control panels, a main panel and an auxiliary panel, wherein the auxiliary panel has a serial communication interface (hereinafter referred to as a serial port), and the main panel has at least two serial ports. The auxiliary panel makes data communication with the main panel via the serial port, while the main panel makes data communication with the auxiliary panel via the serial port and with an upper computer (e.g. PC) via the other serial port. The auxiliary panel cannot make data communication directly with the upper computer, so it must make data communication with the upper computer via the main panel. For example, when the auxiliary panel wants to transmit data to the upper computer, it must first transmit the data to the main panel which then transmit the data to the upper computer, and when the upper computer wants to transmit data to the auxiliary panel, it also must first transmit the data to the main panel which then transmit the data to the auxiliary panel.
The inventor finds out that there are three defects in the above communications: (1) the main panel has a plurality of serial ports which leads to high cost; (2) processing burden of the main panel is heavy, which degrades the system performance; (3) controller programs for the main and auxiliary panels are different, which makes maintenance difficult.